The Department publishes a quarterly index of local bus fares from 2005 onwards.
The information can be found in the table at:
In the 8 years between March 2010 and March 2018, bus fares in England increased by 11.9% in real terms (adjusted for inflation using CPI). By comparison, in the 5 years between March 2005 to March 2010, bus fares in England increased by 12.7% in real terms (adjusted for inflation using CPI).
The bus market outside London is deregulated and decisions regarding setting the level of fares, is primarily a commercial matter for bus operators.