These two charts depict the trends in Texas state government revenue sources from 1978-2004. The first upper-most chart shows for each source of revenue--including federal funds--its percentage share of total revenue. The second lower chart plots percentage share over time as well with federal funds excluded. Overall, both charts show that sources of revenue other than taxes have grown in importance in Texas. Income from oil and gas taxes and from state lands (much of it in the past generated from oil and gas leases) has declined dramatically, replaced only partially by revenue from new sources such as the lottery. Sales taxes throughout this period have been the state's largest internal source of revenue.