Last year, Uncle Zhang used rectangular reed mats 2 meters long and 1 meter wide to form the largest cylindrical grain storage. This year, he used rectangular reed mats 3 meters long and 2 meters wide to form the largest cylindrical grain storage. How many times is the volume of this year's grain hoard compared to last year's grain hoard?
张大爷去年用长2米宽1米的长方形苇席围成容积最大的圆柱形粮囤，今年改用长3米宽2米的长方形苇席围成容积最大的圆柱形粮囤．今年粮囤的容积是去年粮囤容积的多少倍？
<result>4.5</result>