3.2.2 Crop Mix
The production of cereal crops, fruit, and vegetable influence national PUE, as these crops had relatively lower PUE than that of other crops (Table 3, Fig. 3). Rice’s PUE from 1961 to 2014 varied between 20% and 40%, while the PUE of fruit and vegetable varied between 10% and 30% (Fig. 3a). Regression analysis for individual countries and across 113 countries suggests a generally negative relationship between PUE and the percentage of harvest areas for cereal crops or fruit and vegetable (Table 4). These results imply the importance of improving the PUE of low-efficiency crops to improve national PUE.