original: In the past 20 years or so, many new anchor designs have appeared.
simplifications: New anchor designs have appeared over the past two decades. In the past 20 years, many new anchor designs have been created. There have been many new anchor designs in the past 20 years. In about the past 20 years, many new anchor designs have come. In the past 20 years, many new anchor designs have shown up. Many new anchor designs have come out in the past 20 years. In the past 20 years new anchor designs have shown up. Many new main stay designs have come about in the last 20 years. Many new anchor designs have appeared within the past 20 years. A number of new anchor designs have appeared in the last 20 years or so.