|IME Exchange (Including spot, credit and forward transactions)|2007/08|2008/09|2009/10|2010/11|2011/12|
|---|---|---|---|---|---|
|Agricultural - Volume (thousand tons)|273.0|173.5|175.2|1,633.9|550.0|
|Agricultural - Value (billion rials)|772.6|3,729.7|484.8|3,729.0|3,793.0|
|Manufacturing and Metal - Volume (thousand tons)|6,443.8|6,679.7|7,438.5|8,694.0|11,685.0|
|Manufacturing and Metal - Value (billion rials)|58,044.2|62,120.6|53,842.0|75,235.5|102,356.0|
|Oil and Petrochemical - Volume (thousand tons)|89.7|4,339.2|7,052.9|6,662.6|8,117.0|
|Oil and Petrochemical - Value (billion rials)|352.7|19,921.0|36,450.7|41,478.0|64,370.0|
|Grand Total - Volume (thousand tons)|6,806.5|11,192.4|14,666.6|16,990.5|20,351.0|
|Grand Total - Value (billion rials)|59,169.4|82,685.3|90,777.5|120,443.2|170,519.0|

Question: in how many years was the value of agriculture, in billion rials, greater than 500 in iran?
Answer: 4