Interest on debt data comes from the U.S. Census Bureau's Annual Survey of State Government Finances Tables.
The "definitions" at their website do not define "Interest on Debt" explicitly, but they do define "Interest Expenditure" as "amounts paid for the use of borrowed money. Interest on utility debt is included in Utility expenditure."
Interest on Debt Per Capita is the total interest on debt divided by the U.S. Census Bureau population of the state. The U.S. Census Bureau Population Bureau estimates are from U.S. Census Bureau, Population Division, Table: PEPANNRES - Annual Estimates of the Resident Population: April 1, 2010 to July 1, 2019.
Interest on Debt Ranking ranks the states from 1-50 based on the amount of interest on debt per capita, with the number one being the highest amount of interest on debt and 50 being the lowest amount of interest on debt per capita.
For analytical purposes, we have also indexed this data point to 2005. Accordingly, 2005 = 1, and any value greater than one indicates growth over 2005, while any value less than one indicates decline.