determining percent ownership

Hi,

I am trying to determine the percent ownership for each of 4 partners in a new speciality licensed business.
contributions for each are as follows

me= know the local market, initial survey and location plus in future manage and run the licensed business as a manager
person2 is in similar business and has lot of ideas and expertise to incorporate
person3 he introduced me to person2
person4 contributes his name to title and credit to get lease started

offer on table
me 40%
person2 25%
person3 25%
person4 10%

i want atleast 50%. please let me know if it is fair.

thanks