可用于按周统计数据的相关需求，返回0~53周
用法 : yearweek(date,[mode])，mode可选填，默认为以周日为当前周的第一天
可选参数：
| Mode | First day of week | Range | Week 1 is the first week … |
| 0 | Sunday | 0-53 | with a Sunday in this year |
| 1 | Monday | 0-53 | with more than 3 days this year |
| 2 | Sunday | 1-53 | with a Sunday in this year |
| 3 | Monday | 1-53 | with more than 3 days this year |
| 4 | Sunday | 0-53 | with more than 3 days this year |
| 5 | Monday | 0-53 | with a Monday in this year |
| 6 | Sunday | 1-53 | with more than 3 days this year |
| 7 | Monday | 1-53 | with a Monday in this year |
