Tribal casinos reported nearly $30b in gaming revenue last year while posting their largest year-on-year revenue gain in a decade.

Figures released Tuesday by the National Indian Gaming Commission (NIGC) show tribal gaming revenue of $29.9b in 2015, up 5% from 2014’s numbers, which were up only 1.5% from 2013’s total. In 2006, total revenue was $24.9b.

Of the seven geographic regions into which the NIGC groups tribal gaming operators, the Sacramento region (California, Northern Nevada) posted the largest year-on-year gain at 8%. Oklahoma City (Western Oklahoma, Texas) ranked second with 6.7%, while Tulsa (Kansas, Eastern Oklahoma) placed third with 6.5%. All seven regions posted growth last year compared to five year-on-year gainers in 2014.

Sacramento’s 71 operations held on to their grip atop the geographic revenue chart with $7.9b, up from $7.4b in 2014. The 31 operations in the Washington, DC region – which runs along the east coast from Connecticut to Louisiana and as far inland as Missouri – ranked second with $7b, a gain of $200m from 2014, while the 134 operations in St. Paul (from Michigan to Wyoming) gained $100m to $4.8b.