In the absence of a valid agreement, the court shall presume that all marital property is to be divided equally between the parties, but may alter this distribution, without regard to any attribution of fault to either party which may be alleged or proved in the course of the action, after a consideration of the following:
(1) The extent to which each party has contributed to the acquisition, preservation and maintenance, or increase in value of marital property by monetary contributions, including, but not limited to: