Why the static variable is not set to 1000 [duplicate]

I have a static variable in my class , which I instantiate in the cpp file to value 1000.

class Container
{
private: 
    static long GLOBALID;
    long MyID;
public:

    Container();
    long GetId();   
};

The code for cpp file.

long Container::GLOBALID = 1000;

Container::Container()
{
    MyID = GLOBALID++;

}

long Container::GetId()
{
    return MyID;
}

When I print the ID value of container objects, they keep incrementing.

My question is that when I create a new object I instantiate the static varible to value 0f 1000 so why does it keep incrementing with each object created?