function getBonusByDate() view returns (uint256){
        if (block.timestamp < 1514764800) return 0;
        if (block.timestamp < 1521158400) return 40;
        if (block.timestamp < 1523836800) return 30;
        if (block.timestamp < 1523923200) return 25;
        if (block.timestamp < 1524441600) return 20;
        if (block.timestamp < 1525046400) return 10;
        if (block.timestamp < 1525651200) return 5;
        return 0;
    }