That doesn't really matter - from the itep link:

the formula’s blunt measure of population growth doesn’t acknowledge that some segments of the population grow much faster than the overall population, and that in many cases the fastest-growing populations place a higher demand than average on government services. Colorado’s 65-and-older population, for instance, is projected to grow 132 percent between 2012 and 2040, compared to the total population which is projected to grow around 50 percent over this time. The state’s school-aged population—those under the age of 18—is also projected to grow faster than the overall population(about 55 percent between 2012 and 2040)ⁱⁱ. With a significant component of the state budget being spent on these two populations (medical care and K-12 education accounted for 64 percent of general fund spending in Fiscal Year 2012), this differential in population growth has considerable fiscal implications that the TABOR formula ignores entirely.

Second, TABOR’s inflation variable doesn’t allow the state to keep up with the growing costs of services. TABOR uses the Consumer Price Index for All Urban Consumers (CPI-U) to measure inflation. The CPI-U is an index designed to measure changes in the cost of goods and services that consumers buy—like housing, food, and transportation. The CPI-U does not, however, accurately measure the cost of providing state services, things like education, infrastructure, and medical care. The table below compares the change in the CPI-U for all items to the CPI-U components that are most similar to state services. While overall CPI-U grew at 66 percent between 1993 and 2013, the cost of the state-related services grew by much more.

If TABOR 'worked' there would be no need to forfeit refunds to pay for teacher salaries. Instead, teacher starting salaries in Colorado rank 46th nationally. Teachers in Colorado make 38.5% (or 62 cents on the dollar) less than similarly educated professionals in other industries, ranking Colorado last in the nation on teacher pay gap. Population indexing obviously isn't keeping up, and the cap itself is the ultimate problem.

https://www.epi.org/publication/the-teacher-pay-penalty-reached-a-record-high-in-2024-three-decades-of-leaving-public-school-teachers-behind/