The Act 1 of 2006 Index regulates the rates at which each school district can raise property taxes in Pennsylvania. Districts are not allowed to raise taxes above that index unless they allow voters to vote by referendum, or they seek an exception from the state Department of Education. The base index for the 2011–2012 school year is 1.4 percent, but the Act 1 Index can be adjusted higher, depending on a number of factors, such as property values and the personal income of district residents. Act 1 included 10 exceptions, including: increasing pension costs, increases in special education costs, a catastrophe like a fire or flood, increase in health insurance costs for contracts in effect in 2006 or dwindling tax bases. The base index is the average of the percentage increase in the statewide average weekly wage, as determined by the PA Department of Labor and Industry, for the preceding calendar year and the percentage increase in the Employment Cost Index for Elementary and Secondary Schools, as determined by the Bureau of Labor Statistics in the U.S. Department of Labor, for the previous 12-month period ending June 30. For a school district with a market value/personal income aid ratio (MV/PI AR) greater than 0.4000, its index equals the base index multiplied by the sum of .75 and its MV/PI AR for the current year. In June 2011, the Pennsylvania General Assembly eliminated six of the ten the exceptions to the Act 1 Index. The following exceptions were maintained: 1) costs to pay interest and principal on indebtedness incurred prior to September 4, 2004 for Act 72 schools and prior to June 27, 2006 for non-Act 72 schools; 2) costs to pay interest and principal on electoral debt; 3) costs incurred in providing special education programs and services (beyond what is already paid by the State); and 4) costs due to increases of more than the Index in the school's share of payments to PSERS (PA school employees pension fund) taking into account the state mandated PSERS contribution rate.