housing permits meaning in English

住房营建批准数
住宅营建批准数

" certificate " and " real estate " or " property of all housing permits , " what difference , why produce the new " real estate certificate "
《房地产证》与《房屋所有权证》或《房产证》有什么区别、为什么要换发新《房地产证》？
Between 2003 and 2006 , the county issued an average of 530 new housing permits a year , compared with an average of 167 a year in the previous three years
2003至2006年间，县城每年平均颁发530张建房许可证，而此前三年年均仅167张。