The Department of Agriculture says the bird flu killed nearly 20 million egg laying chickens last year, affecting the price of eggs for you. Now, the Consumer Price Index says egg prices have jumped by almost 37% from what they were this same time last year.

The average price of a dozen large, grade-A eggs was $4.15 in December, up from $3.65 in November, according to the Bureau of Labor Statistics. Egg prices were also up more than 36% year-over-year in December, according to the Consumer Price Index.

An ongoing bird flu epidemic has forced farmers to kill millions of egg-laying hens, leading to a serious shortage. The low supply of eggs means customers end up paying quite a bit more than usual at the supermarket. In some places, eggs now cost more than double what they did six months ago.