(2) In furtherance of the policies adopted pursuant to subsection (1) of this section, and in such manner as the commission considers proper, the commission may authorize periodic rate adjustments for the purpose of providing some protection to a utility from reduction of short-term earnings that may result from implementation of such policies. The adjustments may include, but are not limited to, adjustments based in whole or in part upon the extent to which actual sales deviate from a base level of sales the commission considers appropriate. [1993 c.175 §3; 1999 c.944 §3]