Will a change in the definition of "reference transaction" have any impact on these declining numbers?

A 34% drop since Wisconsin's peak year of 1998, a year before the Wisconsin Public Library Service Data reported the number of public access Internet computers in public libraries.

Source:  Wisconsin Public Library Service Data

Wisconsin Public Library Annual Report: What’s New  Reporting Library Activities for 2014. (Wisconsin Department of Public Instruction)

To reflect changes in the types of reference requests that libraries receive, the federal definition of reference transactions has been revised. 

Reference Transactions are information consultations in which library staff recommend, interpret, evaluate, and/or use information resources to help others to meet particular information needs. A reference transaction includes information and referral service as well as unscheduled individual instruction and assistance in using information sources (including web sites and computer-assisted instruction). Count Readers Advisory questions as reference transactions.

Information sources include: 

• printed and non-printed material  

• machine-readable databases (including computer-assisted instruction) 

• the library’s own catalogs and other holdings records  

• other libraries and institutions through communication or referral

• persons both inside and outside the library.

When a staff member uses information gained from previous use of information sources to answer a question, the transaction is reported as a reference transaction even if the source is not consulted again. 

If a contact includes both reference and directional services, it should be reported as one reference transaction. Duration should not be an element in determining whether a transaction is a reference transaction

The article cited here doesn't fully reflect my own view of reference services, but I found this particular quote instructive.

From the concluding section of Re-conceptualizing the ‘reference transaction':   the case for interaction and information relationships at the public library reference desk by Mary Cavanagh University of Toronto, Toronto, Canada.

From a management perspective, the needs are different. Library administrators are constantly reviewing their priorities and services to allocate funds in the most effective means possible while meeting their institutional goals and objectives . Reference desk work has only typically been measured through ‘stick counts’ on annual surveys, aggregated across all branch libraries into one number.

But such quantification misses capturing some of these significant dimensions of the reference process – knowledge and knowing are present, knowledge sharing can be more mutual and users often come to their library with prior experience of relationship, regardless of whether or not that particular interaction shows evidence of this relationship in the moment. And in certain settings, evidence suggests that even silence can speak volumes about information and knowledge connections.

As a library administrator today, I'd be more interested in the amount of time that reference desk staff spend interacting with the public, not the number of actual transactions.

For the sake of example, let's say a full-time Adult Services Librarian is scheduled to work the reference desk 20 hours per week.  What percentage of his or her time -- how many of those 1200 minutes -- are spent in "reference transaction" mode?   And how much time was spent in duties that just as easily could have been accomplished off-desk?

A low percentage might not necessarily be attributable to a lack of business.  It may indicate the need for additional training,  perhaps in the areas of verbal and nonverbal communication skills.  It would also provide opportunities for roving.