请阅读下面这张Markdown格式的表格并回答问题。同一行中不同列的单元格用'|'分隔，不同行的单元格用'
'分隔。

表格标题:
38 图表：重点城市新房成交周数据  
表格:
| 城市 | 销售套数05.20-05.26 | 销售套数05.13-05.19 | 销售套数年度周动均态 | 销售套数环比 | 销售套数较周均变化 | 销售面积05.20-05.26 | 销售面积05.13-05.19 | 销售面积年度周动均态 | 销售面积环比 | 销售面积较周均变化 |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 北京 | 2149.0 | 2049 | 1348.0 | 5.0 | 59.0 | 23.8 | 22.4 | 14.3 | 6.0 | 67.0 |
| 上海 | 1991.0 | 2012 | 2257.0 | -1.0 | -12.0 | 22.6 | 21.9 | 22.8 | 3.0 | -1.0 |
| 深圳 | 1114.0 | 768 | 601.0 | 45.0 | 85.0 | 9.5 | 6.8 | 5.2 | 40.0 | 83.0 |
| 杭州 | 2172.0 | 1980 | 1137.0 | 10.0 | 91.0 | 22.9 | 21.1 | 11.4 | 9.0 | 101.0 |
| 天津 | 1717.0 | 1579 | 1287.0 | 9.0 | 33.0 | 18.1 | 16.7 | 13.5 | 9.0 | 35.0 |
| 南京 | 1176.0 | 1283 | 847.0 | -8.0 | 39.0 | 12.5 | 13.9 | 8.7 | -10.0 | 43.0 |
| 武汉 | 1925.0 | 2284 | 2084.0 | -16.0 | -8.0 | 20.3 | 22.9 | 20.6 | -11.0 | -1.0 |
| 重庆 | 4688.0 | 4650 | 3589.0 | 1.0 | 31.0 | 43.4 | 40.0 | 32.9 | 8.0 | 32.0 |
| 成都 | 1975.0 | 2141 | 1347.0 | -8.0 | 47.0 | 23.8 | 24.3 | 18.2 | -2.0 | 31.0 |
| 青岛 | 374.0 | 1350 | 1386.0 | -72.0 | -73.0 | 2.9 | 12.5 | 13.2 | -77.0 | -78.0 |
| 苏州 | 2925.0 | 2903 | 1543.0 | 1.0 | 90.0 | 31.4 | 30.1 | 16.8 | 4.0 | 87.0 |
| 无锡 | 609.0 | None | 552.0 | None | 10.0 | 7.2 | None | 6.5 | None | 11.0 |
| 福州 | 685.0 | 385 | 297.0 | 78.0 | 131.0 | 7.5 | 4.2 | 3.2 | 79.0 | 134.0 |
| 东莞 | 1230.0 | 1529 | 843.0 | -20.0 | 46.0 | 11.9 | 15.0 | 8.8 | -20.0 | 36.0 |
| 厦门 | 1006.0 | 937 | 500.0 | 7.0 | 101.0 | 10.8 | 10.3 | 5.7 | 5.0 | 90.0 |
| 长沙 | 968.0 | 1500 | 818.0 | -35.0 | 18.0 | 10.5 | 17.1 | 8.9 | -39.0 | 17.0 |
| 昆明 | 1852.0 | 2327 | 1195.0 | -20.0 | 55.0 | 13.9 | 16.4 | 9.8 | -15.0 | 41.0 |
| 惠州 | 437.0 | 397 | 449.0 | 10.0 | -3.0 | 5.2 | 4.7 | 5.2 | 10.0 | -1.0 |
| 一线合计 | 7426.0 | 6809 | 5344.0 | 9.0 | 39.0 | 78.9 | 72.2 | 53.7 | 9.0 | 47.0 |
| 二线合计 | 21567.0 | 23265 | 16736.0 | -7.0 | 29.0 | 219.4 | 228.0 | 172.1 | -4.0 | 27.0 |
| 合计 | 26844.0 | 28025 | 20731.0 | -4.0 | 29.0 | 274.5 | 277.7 | 211.5 | -1.0 | 30.0 |
问题:
我了解到东莞这周的新房销售套数环比不超过30，你知道销售面积环比大概是多少吗？
Answer:
-20.0