Which organ synthesizes more than 90 percent of plasma proteins?

The liver synthesizes most of the plasma proteins, more precisely all plasma proteins are synthesized in liver except for the gamma globulins.\

Plasma proteins(or blood proteins) have many different functions, most commonly transport of macromolecules. Other act as enzymes, complement components or have a function in immunology response.

Serum albumin,  globulins, and fibrinogen are the major blood proteins.