Zeta Mats

When zeta materials were released a little bit more than one year ago, we had only two sources for them available. During the past year we received a few other sources. I remember before the territory wars were released I had a minimum of 1-2 zetas each week from the challenges. Since all the new sources were released I receive max. 1-2 zetas a month from the fleet challenges. It seems that the devs release new sources but reduced the drop rate dramatically for the challenges. I talked to a lot of players in my shard and in my guild, and all had the same feeling/experience. Its really frustrating to have no single zeta from the challnges over more than 7 weeks! ... please post your experiences....