SBD/SP Ratio Chart for Past Year

I was exchanging some Steem Dollar for Steem power earlier today and was surprised to find I wasn't getting many SP. So I went to CMC and download price data for past 12 months to get a gauge on what's a normal ratio.

Needless to say, it's probably not a good time to exchange SBD for SP right now. The current ratio is about 1.2 while the average for past year is 3.12. There might be outliers to screw up the chart, so if anyone can offer some insight, that will be great. Thanks

今天下午轉了一些SBD到SP, 轉完後才覺得匯率好像不太好. 一個SBD差不多換1.2個SP. 所以就去CMC抓了過去一年的匯率, 一看暈倒, 才前陣子一個SBD可以換5個SP. 不過2017也有好一段時期SP還比SBD值錢. 過去一年的平均值則是3.12, 雖然這可能沒什麼意義. 我想下次最少要1:2才會考慮換了.