I am just wondering if my keyword density is about between 1.5 to 2% is very hard for my website to rank? kindly give me advice! Anyway to solve? as I have tries to increase my keyword but some sentence really can't put in!
You are doing good with 1.5 - 2% keyword density. Try to include it in meta description or title together. Combination of meta description, title and contents, will definitely help.
There's no legitimately grounded figure that defines keyword density - simply can't be. Search engines doesn't care about keyword density, all they care about is relevancy, which entails a number of things.
I would worry about your keyword density within certain HTML elements that are important to SEO (<title>, <h1>, <h2s>) FAR more than I would worry about keyword density within the content of the page itself. As others have said, set the <title> to your targeted keyword phrase for the URL. Use the targeted keyword phrase or a slight variation in the <h1> of the page... If possible create a few <h2>s on the page that also target the keyword phrase and slight variations. Include the targeted keyword phrase or slight variations in the URL. Write the content on the page so that it uses the keyword phrase(s) you're targetting but worry more about writing for the reader, not the search engines. 1.5-2% is likely very natural sounding and should be fine.
Yes, 1.5% to 2.0% is good keyword density. Now, just use it in hierachial structure, like H1, H2, etc.