Whisky Price Trend
Well ... you can see the price of single malt which age is over 18 years rise up. And compared with single malt, blended whisky's price is stable.
Taketsuru 21 years old is blended malt or so to speak 'Pure Malt'. the reason why its price has shot up may be the situation that Japanese whisky, especially Taketsuru (Nikka) and Yamazaki (Suntory) has won the prize many times and quite a lot of people want to get them. As a result the price has shot dramatically.
Note: This conclusion is based on just my purchase history in Amazon and Rakuten. Please do not take this seriously!