MEXICO CITY (Bloomberg) -- Mexico spent about 24 billion pesos ($1.25 billion) to lock in prices of oil exports for next year, or more than 21% what it paid to hedge crude a year ago, according to Finance Ministry data.

The cost for buying put options on the market as of the end of the third quarter came to more than the $1.03 billion spent last year to protect against a drop in oil revenue, according to data released in the quarterly budget balance. In recent years, Mexico has spent an average $1 billion buying the hedges.

Deputy Finance Minister Vanessa Rubio said in mid October that Mexico completed its annual oil hedge for 2018. Mexico buys put options from a small group of investment banks each year in what’s considered Wall Street’s largest -- and best-concealed -- annual oil hedge.

Mexico Finance Ministry proposed a 2018 public budget in September projecting oil exports revenue at $46/bbl. Lawmakers increased that assumption earlier this month to $48.5.

Finance Minister Jose Antonio Meade said in an interview in September that Mexico would likely expand its oil hedge marginally for 2018 as it liberalizes gasoline prices, while the cost for the government to protect crude exports against a drastic drop in prices would be about the same as for this year.

The Mexican oil hedge runs from the beginning of December until the end of November. The country has made money three times on the hedge since it started to lock-in prices every year in 2000, including a record payout of $6.4 billion in 2015 after oil prices crashed.